The present invention relates to a washing machine which detects a detergent content and a soiled condition of washing water to control a washing operation, and also to a conductivity detecting sensor for detecting an electric conductivity of the washing water.
In a conventional washing machine, a detergent content and a soiled condition of washing water are surmised by detecting transmittance of light through the washing water to control an washing operation of the washing machine.
Detecting means of the light transmittance includes a transparent pipe provided in a drain passage of the washing machine, a luminous element and a light receiving element which are provided opposite to each other, with the transparent pipe being interposed therebetween. In this type of detecting means, the detection accuracy is adversely affected when the pipe gets contaminated. That is, even if there is no water in the washing machine or the water in the washing machine is clean, the detecting means erroneously detects that the water is soiled due to contaminants on the pipe.